Author(s): Sei Eui Yoon; Jung Soo Kim; Ju Il Song
Linked Author(s): Sei-Eui Yoon
Keywords: Surcharged manhole; Benching; Head loss coefficient; Urban sewer system
Abstract: Energy loss at manholes, often exceeding friction loss of pipes under surcharged flow, is considered as one of the major causes of inundation in urban area. Therefore, it is necessary to analyze head losses at manholes, especially in case of surcharged flow. Hydraulic experiments were conducted with three cases. Case A was to test whether the shapes of the manholes influence head loss coefficients. Case B and C were proposed to further reduce head losses by improving the hydraulic efficiency of manholes. In case B, the joining part of pipes at square manhole was shifted from the center to the edge. The test in case C was to check the average head loss coefficients by installing the side benching in square manhole, based on the shifted joining part model. The average head loss coefficients for circular and square manhole in case A were 1.61 and1.59, respectively. In this case, there was no significant difference of head loss between circular manhole and square one, and also no large variation of head loss as discharges. However, case B and C showed large differences of head loss coefficients due to the strong oscillation of water surface and the vertical swirling motion. The square manhole in case B reduced the head loss up to 6%compared with one in case A-2. The head loss coefficients of the square manhole in case C could be reduced to 1.1. The results might be available to apply to design of urban sewer system with surcharged flow.
Year: 2010